The present invention relates to solid state integrated band-gap type voltage reference circuits. More particularly, this invention relates to band-gap reference circuits wherein the output voltage can be made any multiple of the band-gap voltage in which the output voltage remains substantially constant with temperature variation.
Solid state band-gap references are well known to those skilled in the art which rely on certain temperature dependent characteristics of the base-emitter voltage (VBE) of a bipolar transistor. For example, U.S. Pat. No. 3,617,859 describes such a band-gap reference wherein the negative temperature coefficient of the base-to-emitter voltage of a first transistor in conjunction with the positive temperature coefficient of the base-to-emitter voltage differential between two additional transistors operating at different current densities is used to achieve a zero temperature coefficient reference potential.
Another voltage reference circuit of the type referred to incorporates four transistors which are interconnected, with respective pairs of the transistors having ratioed emitter areas to establish a difference voltage across a reference resistor having a positive temperature coefficient. This positive temperature coefficient voltage across the reference resistor can be used to negate the negative temperature coefficient of the base-to-emitter voltage of another transistor. This particular reference circuit is shown and described in U.S. Pat. No. 3,908,162.
Although prior art voltage reference circuits based on the V.sub.BE characteristics of transistors and discussed above have advantages associated therewith, these types of circuits suffer from some limitations. For instance, these circuits may suffer on accuracy and TC compensation as well as having beta dependent characteristics which are not desired. Therefore, there is a need for an improved temperature compensated voltage reference circuit which overcomes the aforementioned limitations as well as having superior load rejection characteristics. In addition such improved circuit would desirably have load driving capability.